From 2edeaa34a6e3f2c43b667f6c4f7b27944b811695 Mon Sep 17 00:00:00 2001 From: Tetsuo Handa Date: Mon, 7 Feb 2011 13:36:10 +0000 Subject: CRED: Fix BUG() upon security_cred_alloc_blank() failure In cred_alloc_blank() since 2.6.32, abort_creds(new) is called with new->security == NULL and new->magic == 0 when security_cred_alloc_blank() returns an error. As a result, BUG() will be triggered if SELinux is enabled or CONFIG_DEBUG_CREDENTIALS=y. If CONFIG_DEBUG_CREDENTIALS=y, BUG() is called from __invalid_creds() because cred->magic == 0. Failing that, BUG() is called from selinux_cred_free() because selinux_cred_free() is not expecting cred->security == NULL. This does not affect smack_cred_free(), tomoyo_cred_free() or apparmor_cred_free(). Fix these bugs by (1) Set new->magic before calling security_cred_alloc_blank(). (2) Handle null cred->security in creds_are_invalid() and selinux_cred_free(). Signed-off-by: Tetsuo Handa Signed-off-by: David Howells Signed-off-by: Linus Torvalds --- kernel/cred.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) (limited to 'kernel/cred.c') diff --git a/kernel/cred.c b/kernel/cred.c index 6a1aa00..fcf104b 100644 --- a/kernel/cred.c +++ b/kernel/cred.c @@ -252,13 +252,13 @@ struct cred *cred_alloc_blank(void) #endif atomic_set(&new->usage, 1); +#ifdef CONFIG_DEBUG_CREDENTIALS + new->magic = CRED_MAGIC; +#endif if (security_cred_alloc_blank(new, GFP_KERNEL) < 0) goto error; -#ifdef CONFIG_DEBUG_CREDENTIALS - new->magic = CRED_MAGIC; -#endif return new; error: @@ -748,7 +748,11 @@ bool creds_are_invalid(const struct cred *cred) if (cred->magic != CRED_MAGIC) return true; #ifdef CONFIG_SECURITY_SELINUX - if (selinux_is_enabled()) { + /* + * cred->security == NULL if security_cred_alloc_blank() or + * security_prepare_creds() returned an error. + */ + if (selinux_is_enabled() && cred->security) { if ((unsigned long) cred->security < PAGE_SIZE) return true; if ((*(u32 *)cred->security & 0xffffff00) == -- cgit v1.1 From fb2b2a1d37f80cc818fd4487b510f4e11816e5e1 Mon Sep 17 00:00:00 2001 From: Tetsuo Handa Date: Mon, 7 Feb 2011 13:36:16 +0000 Subject: CRED: Fix memory and refcount leaks upon security_prepare_creds() failure In prepare_kernel_cred() since 2.6.29, put_cred(new) is called without assigning new->usage when security_prepare_creds() returned an error. As a result, memory for new and refcount for new->{user,group_info,tgcred} are leaked because put_cred(new) won't call __put_cred() unless old->usage == 1. Fix these leaks by assigning new->usage (and new->subscribers which was added in 2.6.32) before calling security_prepare_creds(). Signed-off-by: Tetsuo Handa Signed-off-by: David Howells Signed-off-by: Linus Torvalds --- kernel/cred.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel/cred.c') diff --git a/kernel/cred.c b/kernel/cred.c index fcf104b..3a9d6dd 100644 --- a/kernel/cred.c +++ b/kernel/cred.c @@ -657,6 +657,8 @@ struct cred *prepare_kernel_cred(struct task_struct *daemon) validate_creds(old); *new = *old; + atomic_set(&new->usage, 1); + set_cred_subscribers(new, 0); get_uid(new->user); get_group_info(new->group_info); @@ -674,8 +676,6 @@ struct cred *prepare_kernel_cred(struct task_struct *daemon) if (security_prepare_creds(new, old, GFP_KERNEL) < 0) goto error; - atomic_set(&new->usage, 1); - set_cred_subscribers(new, 0); put_cred(old); validate_creds(new); return new; -- cgit v1.1